Coded track circuit signaling systems



July 29, 1952 T. J. JUDGE CODED TRACK CIRCUITSIGNALING SYSTEMS 2 Sl-lEETS-SHEET 1 Filed Oct. 13, 1948 FIG. 1.

y; INVENTOR. BY

ywaye, 1i

HIS ATTORNEY July 29, 1952 J JUDGE 2,605,390

CODED TRACK CIRCUIT SIGNALING SYSTEMS 2 SHEETSSHEET 2 s 75 50 R 51 R R INVENTOR.

Hi5 ATTORNEY Patented July 29, 1952 GODED TRACK CIRCUIT SIGNALING SYSTEMS Thomas J. Judge, Rochester, N; Y., assignor to GeneralwRailway Signal Company, Rochester,

NLY.

Application October 13, 1948, Serial No. 54,275 I 7 6 Claims.

This invention relates to signalling systems for railroads employing codedtrack circuits, and

v more particularly to apparatus for checking the integrity of the insulated joints in the railroad track adjacent signal locations and preventing improper signal indications in the event of failure of such insulated joints. t

In'sometypesof; coded track circuits for the control of automatic block signalsand the like, a breakdown or failureof theinsulated joints in the track .rails electrically separating adjoining track sections tends to .permit energization of the code following track relay of one'track section by the application ofcoded energy to the track railsof the adjoining track sect-ion, sothat improper coding operation .orsuch track relay may occur and cause an improper signal indication or the like. In certain types of systems, this contingency of improper operation in coded track circuits in the event of defective insulated joints may be avoided byemploying a code following track relay atone side of theinsulated joints whichrequirescurrent of a certain polarity orother distinctive characterfor its operation, and by. applying currentof. a dilierent polarity r character.tothe track-rails of the adj'oiningtrack section on' the other side of. said insulating joints, so thatafalseor improper codingoperation of the track relay cannot be reproduced-by energy iedfrom the adjoining track sectionthrough the defective insulated joints. not be employed where alternating current of the same frequency, or code pulses of different polarities at different times, are employed for operationof the code following tr-ackrelays.

,Itisproposed inaccordance with the present invention to provide apparatus for use withcoded track circuits energized byalternating current or code pulses of differentpolarities, which will automatically check the integrityof the insulated joints separating adjoining track. sections at. a signal location or thelike, andivhich automatically prevents a-false or. improper coding operation if the insulated joints are defective.

Generally speaking, byway of explanation and without attempting to define the nature and scope of this invention, circuit means is provided 'for the track section associated With a signal location or .the like so that, when this track section becomes" unoccupied and its track This expedient .ca'n

relay maybe operated, improper energization-ofi this track relay by energy fed from an adjacent track section through defective insulated i join'ts automatically results in a steady energizationof" this adjoining track section and said'track relay,

rather than an improper coding operation of fithe relay; and auxiliary relay means is provided-so that the steady energization ofthe' adj'oming track section under "such conditions 'followin'g a previous coding operation does notcaus'ef a similar steady energization of a track" section in the rearof it.

Various other characteristicfeatures, at'tributes, and advantages of {this invention-, 'both in its broad and specific aspects, will bein part: apparent and in part pointed outas' the descrip-- tion progresses.

The accompanying drawings illustrate in a simplified and diagrammatic manner one forum of the invention as applied to a typical automatic block signalling system using alternating current coded track circuits, the parts-and'cir cuitsbeing-illustrated more with a view-offacil itating an explanation and understanding of the nature of the invention, than for the purpose of showing the specific details of construction and arrangement of parts and circuits prefer? ably employed in practice. In 'these drawings, Fig. 1 illustrates in the normal operating condition the apparatusga'ndj circuits which are associated with a typical signal location of an automatic block signalling system of the type contemplated; V Figs. 2A to 20 illustrate this'apparatus'iniits different operated conditions; and v Fig. 3 is a diagrammatic representationv of the. conditions of the tracksections fora number of signal locations when defective insulated joints at one of these xsignal locationshas beenauto-r' matically detected and manifested inaccordance with this invention. The typical embodiment of the invention illustrated relates to an automatic block signalling. system for multiple track railroads using coded track circuits energized byalternating current In such a system, the railroad track is divided into blocks by insulated joints in thetrack rails in the usualway, and a signal at the entrance end 'to each block has its favorable or pro'ceed indications controlled in accordance with the be readily adapted to coded track circuits for.

other applications and uses; but an explanation and understanding of such a typical' embodiment of the invention will serve to make clear the characteristic features, functions, and mode of operation characterizing the invention. In this connection, it was convenient to assume that each block comprises a single coded track circuit, but various variations in the way of cut sections, special sections for the control of highway crossing signals, and the like may be employed.

Referring to Fig. 1, the invention is employed for detecting the integrity of insulated joints I which are adjacent a signal S and separate a rear track 'section TI and a forward circuit track section'TZ. Each of these track sections TI, T2 represents a block in a block signalling system, and each track section is equipped with conventional: apparatus and circuits to constitute a typical alternating current coded track circuit. Such alternating current coded track circuits are particularly useful for railroads using electrical propulsion; and the impedance bonds for such an application aregshown diagrammatically at 2 in Fig; '1. The signal S, which may be of any suitable type, in the interests of simplicity, is assumed to' be a color light signal having lamps with lighting-circuits controlled by relays H and D to display theusual green, yellow and red aspects for clear, caution and stop indications.

The coded track circuit equipment is the same foreach blockor track section in the type of system assumed, and comprises in general code associated circuits more conveniently discussed later, which operates a contact 3 in the primary circuit of a transformer T, which is connected to the terminals of a suitable'sourcc of alternating current indicated by BX and CX. The secondary of the transformer T is coupled to the impedance bond .2 in the usual manner, so that when relay CPR "is energized,an alternating current is applied across the track rails at the exit end of the track section TI.

The code receiving apparatus comprises a code following track relay TR, which is connected through a suitable full wave rectifying unit 4 to a winding 5 coupled to the impedance bond 2 for the track section T2. This code following track relay'TR may be of the biased polar type for sensitivity and quick response, but is essentially a quick acting relay energized by rectified alternating current supplied from the track section T2; The track relay TR operates contacts I and 8 which control decoding means of the usual type to cause energization from the relay H when this track relay is intermittently energized at any code rate,'and a relay D when this track relay is intermittently energized at a predetermined code rate for a clear indication, such as 180 times per minute. The decoding apparatus shown, which may take various forms, is disclosed in various prior patents, such as F. X. Rees, No. 2,353,930, dated July 18, 1944, or T. J. Judge, No. 2,350,620, dated June 6, 1944, so that an explanation of the detailed structure and operation of the decoding apparatus is unnecessary.

The coded track circuit equipment for the signal location also includes'a suitable code oscillator or motor driven transmitter for operating contacts 150T and I80CT for the 75 and 180 code rates. This is conventional equipment and need not be further discussed.

A coded track circuit equipment at each signal location also includes in accordance with this invention an auxiliary stick relay CR of the conventional neutral type with ordinary operating characteristics.

- The various circuit connections are illustrated in a simplified manner, with the symbols and associated'with arrows to indicate terminals with suitable source of direct current.

Operation.Fig. 1 illustrates the apparatus and circuits associated with the signal location in the normal operating condition when no trains are present, and the track sections TI and T2 are supplied with alternating current code pulses at the 180 code rate. Under such conditions, relays H and D are both energized by the intermittent operation of the track relay TR and its contacts 1 and 8 at this 180 rate. The relay CR is energized by a circuit which may be traced from through front contact I of code following track relay TR, through a rectifier I0, and either front contact II of relay H or front contact I2 ofrelay CR. In other words, boththe pick-up and stick circuits for the relay CR are established under these normal operating conditions. The transmitter relay CPR is connected to the coding contacts ICT operating at the code rate by a circuit which may be traced from through coding contacts I80CT, front contact I! of relay H, front contact I6 of relay CR, and relay CPR, to Contacts I4 and I5 of relays H and D establish a lighting circuit for the green lampG.

'While the insulated joints of the usual type in construction may lose their insulating qualities and become defective or break down at any time,

and independently of train movement, a broken down joint condition is usually created as a result of a train movement over the joints; and since it is the presence of a train which renders improperrcoding operation due to defective joints unsafe, it is expedient to discuss the operation of this invention under the condtions where a train has passed the signal S and has rendered the insulated joints l defective in so doing.

When a train passes the signal S and occupies the track section T2, the relays and circuits assume the condition illustrated in Fig. 2A. The track relay TR is shunted by the train and remains in its deenergized position, opening at its front contact I both the pick-up and stick circuits for the relay CR. The relay H is also de-' energized. Under these conditions, the transmitter relay CPR is connected to the coding contact I5CT operating at the 75 code rate by a circuit which may be traced from through contact 750T, back contact I6 of relay CR, back contact I I of relay H, and winding of relay CPR, to the 75 code rate to provide a caution indication for the signal (not shown) next in the rear of signal S.

In order to indicate the utility and significance Thus, the track section TI is coded at anon-.39

'3 i1 vs'hereth train. n: ques n ha dvaneedmeand; thenext-s gnalflotat n: d-wacat t rackection Tl; v

it, Qiith s n entio separat d-hm v applied to the .rear of the track section due 'IllQibIQkBnndQi/Vn; condition" or the; insulated 2* ints-Leyentthouehe, eei-tima eiy od isflpmwi edufonth trac. sectl nfrzex su hnc di ea pration I ;':1 Ql fi' k) relay TE n rs z sirs y H =wwhichzcauses;thecode ratesupplied toyt ew -;trackr-zsection;7T2; to abeichanged, to \the 180; code wrateu an isuch p1 0; cod rate i qfe r gh t :defectiveginsulated joints, and -0r era te s the track :ielay TR togcausei signal S; to-indicategreen-or 'p 0ceed. 6VBni.th01/lgh the -.tra111-; mayv ein t 'inext block in :adrance and asz owor cauti dicat ion should lie-displayed; Theior.egoing ;dis-

icussionzassumesthat thedegil matelcode i on the ,-.track sec-tionz E12 isrnot present, due; to "a hrolzen rail on Luther: defectglibut; even if tirnatep '75 .mcdeexists in tracksectionzli defec ,vemnsulated i. joints-37811161*PfilfllitsCOdB. at the: 1. it teiin ra wsectionjT-Lto besnppliedtmt ac section Tzand .-:esta;blish interferin 7 or; .heat .-;e0 ee nd tion :whichi arelikely: to; causeverraticzand cas on --=fa1se. indications forthe signal Sin, 7 H

g Gonsidering now;the operation ot;-the-=- sy stem undensirnilar. conditionswithsthe protective :tures; provided shy: this invention, and :Eeferring.

to Fig.--2B;;:when.the train in. track isedtion T2 has "advanced i t'oatheepoint Where. its wheel shunt is noilonger' efiective to,. ..prevent ienergrization of the tra'clerelay TB, the; initial 1 energization: of this "jfflCki-TGlQ-Y TR, i-whethery. by a: legitimate-code xpu-lsa or. by a code pulse iedthrou h: thegdefectwe 4 insulatedoints alonathe circuit-paths, frommhe arear-maclnsection :Ti; establishes, acircuit to: en-

ergizc the transmission relay; GPBt'sw-hich may be traced=ifromx(+)i, through frontl. ;-co ntact ,7; of etrack relayiTR,.rectifier l0,.- .backcontacti H, of relay H, hack. contact.- tB: of: relay; (3B,: andrelay wGPR; to. It FWii'l be; noted that: this :circuit izjust traced will maintainzthe relay CBRenergi-zed independently of theopening. oftheicodingeom.

etacts 1501: If, assassumed theiinsulatedijoints are defective;v the ia-lternating .c voltage, gapplied t across the "track rails of the: reanwtraclezsedtion -'=Tl 'byi'the energized.- condition ottransmitter relay :CPR is effect-metevmaintaingthecode ,folloW- ing track relay TB: of the forward track: section --energ ized. Gonsequently', in the case; of v the defective insulated joints;steady energy is supplied to the real track-section T i and also to; theitraclc relay TR of-the forward tracksectiomTZ; Under such =-conditions; regardless of; :whether. or not :there-is a 'legitimatecode miracle-section T2, the trackrelay Y'IR remains. energized;;.az1d:likewise L the relaysHan'd D-remainadeenergizedto provide astop indication.

' flhe z i-vr u t-means-a t ng: to che k the ntesrity o the insulated-ioints atlocation of; signal S upon tial energization of; the-track relay TR, after N the forward track section 1127 becomes unoccupied, and Ionautomatically creatingasteady energized nlocked up (condition of the-system; as. just desc be i n :.lud s:t aba kv t c l8; ithee y ';QR and- =this relay serves to; rendert-his circuit mea'ns -inefiectivefor a track section in a, coding 1O condition at the-itime steady energy is applied, sothatthe steady energization of -.the-;rear track: .asectionTI in the manner just explained will notin u n a se a ea ly n s ati n 0f. the ra isection next in therearof it and so oni Con-- 15-; sider inghowa the relay CRrperforms this function, d-referringtofilig. 2Cwhichillustratesthe con- $1 1 Qf t e; t p l apparatus at signal Sl of. 151s ties-sa tha the tracks ctm -I: n-th s t me 2. 1 eins cpd at thet met est a y e 20.;ergy; is ;appl ied thereto; as indicatedin l ig -ZA. Under these conditions, when the steady energy is applied to the track section Tl,,the;relay IH for this track section is energized due to -the pre- --ryious feeding operation,'- and; relay; 1GB, isener- 25, gizede Consequently; when the steady energy is applied; to the rear 'tracksection Tit on account of thedefective; insulating, Joints: and the track. relayiTR ofthe rear traclssection T! has been maintainedsteadilyenergizedlong enough tore- 30. lease its relay 1H; -the relay, ECR; ispmaintained energized by the stick circuit throughits front H contact i-fit-q-and; the; circuit, causing steadyene-rgization of the; rear track, section TQ-preyious- 1 described for traclssection (Ti and; shown in i F st is rok t h ack contac I f; re y ica. .Th st ew d n .st ad tener i at is not-repeatedtor; a cascaded, as ,-otherwise mi ht occur Under-these conditions illustrated in- Fig. 2G; thecode transmitter ECPH-for the-rear track 40 section TO-;remainsdeenergized the-circuit for --the75icode beingnpened atthe back contact l5 ofrelay l-CR, and its circuit for thelSO codebeing opened at the front con-tact H ofrrelay H.

-;Thus,sis-diagrammatically indicated in Fig. 3,

. ;*\t=hende-fective insulated-joints at a-givensignal ransiormer; andtherectifier Wis preferably in- ;cl ude d inthe-control circuits for relayCR, so that under the conditionsillustrated in- Fig. 2A, for-exarnpla-this winding of the decoding transformer m o be ntermit y I er d y p tion of;; -thecode transmitter 1contactfl5CT, as *nightotherwise occur due tothe circuit connectionsthe nset up except for this rectifier. g; firomth e-ioregoin it can be, seen howthis inrrent ons n-rovidescau oma p o e za a n a ialse clear, signal-indication or similar improper ,operation of encoded track circuitdue toa break i ,downof,;the;insulated .joints, .that would other- 7 wisepermitthe code fOllOWingtIfiOk: relay of one 7 ,:;tr,ack,- sectionto. be improperly operated by code ;,;pu1ses1 applied to-an-adjacent .trackisection. It will bernotedthat these protective features do not depend upon staggered, polarity onthelike, and 75. permitalternating current of .code pulses" ofdifferent polarities under different conditions to be utilized for the operation of coded track circuits. It can also be seen that these protective features are obtained by the operation of the code following track relay itself, in combination with auxiliary stick relay CR, and the signal control relay H, without relying upon relative-times for the energization and release of these relays, or other relays such as slow release front or back contact repeaters of the code following track relay.

The characteristic features and operating principles of this invention may be employed in different ways for different types of coded track circuit systems, other than the particular type of alternating current coded track circuit system illustrated; and I desire to have it understood that various adaptations, modifications and additions may be made in the specific embodiment of the invention shown and described, and-in its field of use, without departing from the invention. v

What I claim is:

1. In a coded track circuit signalling system for railroads, the combination of adjoining track sections separated by insulated joints, a code following track relay connected across the track rails at the entrance end of the forward track section, code transmitting means including a code transmitter relay for applying energy across the track rails at the exit end of the rear track section at different code rates dependent upon traffic conditions, said code transmitting means including circuit means for applying energy to said code transmitter relay through a front contact of said track relay upon the initial energization of the track relay for the forward track section and so long as that track relay is continuously thereafter maintained energized, and means responsive to the intermittent coding operation of said track relay and also a steady energization thereof following such intermittent coding operation for rendering said circuit means ineffective, whereby improper energization of said track relay by energy fed through defective insulated joints from the rear track section causes a steady energization of that track section and said relay, and whereby the steady energization of the rear track section under such conditions does not cause a similar steady energization of a track section in the rear of it similarly equipped.

2. In a coded track circuit system, a circuit and relay organization for manifesting failure of insulated I joints separating adjoining track sections comprising in combination, a code responsive means for the entrance end of the forward track section including a code following track relay and a signal control relay energized only by the intermittent coding operation of said track relay, a stick relay having a pickup circuit dependent upon the closure of a front contact of said signal control relay code transmitting means for applying energy across the track rails at the exit end of the rear track section, and a circuit including a front contact of said track relay and a back contact of said signal control relay and a back contact of said stick relay for operating said code transmitting means, whereby the integrity of the insulating joints is checked when the forward track section become unoccupied by causing a steady energization of the rear track section and said track relay for the forward track section when energy may be fed from the rear track section to the forward track section through defective insulated joints.

3. In a coded track circuit system for railroad 1 tracks divided into tracksections by insulated joints and having code transmitting and code receiving means for each track section, said code receiving means including a code following track relay and a signal control relay energized only in response to the intermittent coding operation of said track relay, circuit means for controlling the code transmitting means for the rear track section upon the initial energization of the track relay for the forward track section when it becomes unoccupied to maintain a steady energization of the rear track section until said code following track relay for the forward track section is deenergized, and relay means initially operated by the energization of said track relay while said signal control relay is energized and maintained operated after the release of said signal control relay so long as said track relay is energized for rendering said circuit means ineffective 'for steadily energizing the next track sectionin the rear.

4. In a coded track circuit system for railroads, a relay and circuit organization for detecting failure of the insulated joints separating track sections at a signal location and acting to prevent clearing of said signal when said insulated joints are broken down, said organization comprising code transmitting means for applying energy to the track section in the rear of said signal, code responsive means for the track section in advance of said signal including a code following track relay and a signal control relay energized only by intermittent operation of said track relay, a circuit closed when said track relay is initially energized while said signal control relay is deenergized for operating said code transmitting means to apply steady energy to the rear track section, relay means acting while energized to prevent closure of said circuit, and control circuits for said relay means for initially energizing said relay means when said code following track relay and said signal control relay are contemporaneously energized and for maintaining it energized while said code following track relay is energized after said signal control relay has once been energized and is thereafter released.

5. In an organization for detecting the failure of the insulated joints of a coded track circuit for railroads, code transmitting means for applying energy to the track section in the rear of a signal location, code responsive means connected to the track in advance of such signal location including a code following relay and a signal control relay energized only by the intermittent operation of said code following relay, circuit means effective when said code following relay is energized and said signal control relay is deenergized to operate said code transmitting means to apply steady non-coded energy to the rear track section, relay means effective when in a particular position to prevent closure of said circuit means. and control circuit means causing said relay means to be in said particular condition when said code following relay is initially steadily energized when said signal control relay has been energized, said means causing said relay means to be in its opposite position when said code following relay is initially steadily energized with said signal control relay deenergized.

6. A circuit organization for detecting broken down insulating joints at each signal location in a coded track circuit signalling system comprising for each signal location, a code following track relay for the forward track section at that signal location, decoding means including a slow 9 10 release signal control relay energized only by the said stick relays being in their deenergized posiintermittent operation of said code following retions. lay, a normally energized stick relay having a THOMAS J. JUDGE. pickup circuit closed through a front contact of said slow release relay and having its initial ener- 5 REFERENCES CITED gization dependent upon t steady intermit' The following references are of record in the tent energization of said code following relay fil of thi patent; and track circuit code transmitting means efiective to apply selectively steady or coded energy to UNITED STATES PATENTS the rear track section at the associated signal 10 Number Name Date location, said steady energization being selected 2,235,134 Allison Mar. 18, 1941 to be applied dependent upon said code following 2,277,461 Shields Mar. 24, 1942 relay being energized and said signa1 control and 2,369,053 Jerome Feb. 6. 1945 

